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The Impact of Bayesian Hyperpriors on the Population-level Eccentricity Distribution of Imaged Planets

Nagpal, Vighnesh and Blunt, Sarah and Bowler, Brendan P. and Dupuy, Trent J. and Nielsen, Eric L. and Wang, Jason J. (2023) The Impact of Bayesian Hyperpriors on the Population-level Eccentricity Distribution of Imaged Planets. Astronomical Journal, 165 (2). Art. No. 32. ISSN 0004-6256. doi:10.3847/1538-3881/ac9fd2.

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Orbital eccentricities directly trace the formation mechanisms and dynamical histories of substellar companions. Here, we study the effect of hyperpriors on the population-level eccentricity distributions inferred for the sample of directly imaged substellar companions (brown dwarfs and cold Jupiters) from hierarchical Bayesian modeling (HBM). We find that the choice of hyperprior can have a significant impact on the population-level eccentricity distribution inferred for imaged companions, an effect that becomes more important as the sample size and orbital coverage decrease to values that mirror the existing sample. We reanalyze the current observational sample of imaged giant planets in the 5–100 au range from Bowler et al. and find that the underlying eccentricity distribution implied by the imaged planet sample is broadly consistent with the eccentricity distribution for close-in exoplanets detected using radial velocities. Furthermore, our analysis supports the conclusion from that study that long-period giant planets and brown dwarf eccentricity distributions differ by showing that it is robust to the choice of hyperprior. We release our HBM and forward-modeling code in an open-source Python package, ePop!, and make it freely available to the community.

Item Type:Article
Related URLs:
URLURL TypeDescription
Nagpal, Vighnesh0000-0001-5909-4433
Blunt, Sarah0000-0002-3199-2888
Bowler, Brendan P.0000-0003-2649-2288
Dupuy, Trent J.0000-0001-9823-1445
Nielsen, Eric L.0000-0001-6975-9056
Wang, Jason J.0000-0003-0774-6502
Additional Information:V.N., S.B., and J.J.W. acknowledge support from the Heising-Simons Foundation, including grant 2019-1698. B.P.B. acknowledges support from the National Science Foundation grant AST-1909209, NASA Exoplanet Research Program grant 20-XRP20_2-0119, and the Alfred P. Sloan Foundation. For the purpose of open access, the author has applied a Creative Commons Attribution (CC BY) license to any Author Accepted Manuscript version arising from this submission.
Funding AgencyGrant Number
Heising-Simons Foundation2019-1698
Alfred P. Sloan FoundationUNSPECIFIED
Issue or Number:2
Record Number:CaltechAUTHORS:20230123-451320900.27
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Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:118896
Deposited By: Research Services Depository
Deposited On:30 Jan 2023 17:21
Last Modified:30 Jan 2023 17:21

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